A couple who got married in England, found themselves a few years later in the Israeli Rabanut, with the husband demanding a Get, and his wife refusing. The husband, being the Halachically minded type, suddenly remembered that he was a Cohen - and that his wife had been previously married. Since Jewish law forbids a Cohen to marry a divorcee, the Beit - Din must force the couple to divorce. From the Ynet article it is unclear how exactly the couple managed to hoodwink the London Beit Din, and get married in the first place, but the husbands new found respect for his priestly caste did not fall on deaf ears, and the Dayanim were sympathetic to the argument.
The wife, desperate to save her marriage, came up with two counter-arguments: the first was that this was the first that he she had heard of her husband being a Cohen - an argument that even if true, wouldn't really help her. The second argument however, was the type that really makes you proud to be a Jew! she claimed that her husband's mother had slept around with some non Jews. As such - his father was forbidden halachically from marrying his mother - and their offspring are not considered Cohenim (חללים - I know I'm not being exact here). Not to be outflanked halachically, the husband quickly retorted that it was not his mother, but his grandmother who had been living the promiscuous life. As such he was a Kosher Cohen, and g-d forbid that he should remain married to his divorcee wife one moment longer!
The Beit-Din ruled in his favor and forced the wife to accept a Get. (i.e divorce)
A great day for Halacha. The more interesting question would now be, can the wife sue the husband for misrepresenting himself all of these years?